Standard Method of Test For. CDOT CP 76 (CP -L 5101) Laboratory Equipment

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3 8/14/2017 Standard Method of Test For Verification of equipment used to test Asphalt Materials CDOT CP 76 (CP -L 5101) Laboratory Equipment CP 76 This procedure covers the verification of equipment used to field test bituminous mixtures and provides documentation that the equipment verification has been done. 1

4 8/14/2017 CP-L 5101 Verification of Laboratory Equipment Used to Test Bituminous Mixtures Superpave Gyratory Compression Machines Molds, Ram Heads, Base Plates, etc. Also covers gyratory maintenance Stabilometer, molds, followers, calibration cylinder Both procedures contain schedules for maintenance, calibrations and verifications of equipment. Questions???????????? 2

5 8/14/2017 Standard Method of Test For Reducing Field Samples of Asphalt Mixtures to Testing Size CDOT CP 55 Summary Asphalt mixtures must be sampled in accordance with CP 41 (T-168). Samples must be split properly to obtain representative portions. This procedure is valid for asphalt mixtures having a nominal maximum particle size of 1.5 inch (37.5 mm) or less. 1

6 8/14/2017 Representative Samples To ensure representative samples: Employ techniques that are intended to minimize variations in measured characteristics between the test samples. Use proper equipment for the type of material to be reduced in size is important. Equipment must also be used properly to produce representative samples. Splitting Methods Method A-Selection by scoop Method B-Quartering Method C- Riffle type splitter Method D-Selection by cross section 2

7 8/14/2017 Preparation for Reduction to use Methods A, B, D Apparatus Clean small flat square end scoop with sides. Clean large flat bottomed mixing pan. Preparation Method 1 Place sample into large, flat bottomed pan without loss of material. Mix entire sample thoroughly 3 times. Flatten to uniform depth equal to or lower than the sides of the scoop. 3

8 8/14/2017 Preparation Method 2 Place the sample can into the mixing pan with the opening resting on the bottom of the pan (upside down). Elevate the can about 1 inch from the surface and move in a circular motion allowing the material to form a trail behind the can. Try to distribute the material in two or more layers. If visually segregated, mix the entire sample thoroughly and level as in Prep Method 1. Method A-Selection by Scoop Insert the scoop to full depth of the material. Lift scoop with minimal loss of material. Select a minimum of three increments. Small portions may be cut with a putty knife or similar tool for small quantity additions. Combine portions for test specimen of required mass. Save remaining portion until tests are completed. 4

9 8/14/2017 Method B -Quartering Divide the sample into four equal quarters with scoop. Remove two diagonally opposite quarters. Re-mix the remaining two quarters. Repeat procedure until sample is the required mass for the test specimen, save remaining portion until tests are completed. Method C- Riffle Type Splitter Splitters shall have a minimum of 8 chutes for coarse aggregates, 12 chutes for fine aggregates. The minimum width of the chutes shall be approximately 50 % larger than the largest particles in the sample. Place the sample in the mixing pan and mix thoroughly. Two procedures for depositing samples into splitter: Flat scoop equal to width of riffles (feeder pan). Extra splitter pans 5

10 8/14/2017 Riffle Splitter by Scoop (Feeder pan) Remove material using the feeder pan. Pour half of the portion from one side. Reverse the ends of the feeder pan and pour the rest from the other side. Pour slowly to allow a free flowing condition. Continue until the entire sample has been introduced to the splitter. Riffle Splitter by Spare Pans Place the sample into two spare pans placed side by side with scoop. Uniformly distribute the material from edge to edge. Pour ½ of the material into the splitter. Reverse the ends of the pan. Pour the remaining material into the splitter. 6

11 8/14/2017 Feeder Pan or Spare Pans Method Reintroduce the portion of the sample as many times as necessary to reduce the sample to the size specified. Use opposite pans for further reduction. Save the remaining material for additional tests. Method D-Cross Section Push a metal slat vertically through sample. Push a second slat through sample parallel to the first. Remove entire sample between the slats - take care to include all the fines on the tools. Obtain additional samples by pushing one of the slats vertically into the remaining material and repeating the process. 7

12 8/14/2017 Quartermaster Device CP 55 states that this method is used to split large samples for testing between two labs. NO Provisions are made for reducing the sample to testing size using this method. Quartermaster 8

13 8/14/2017 Quartermaster Used for combining & splitting large samples for testing between two or more labs Splitter is to be clean and heated to not exceed 110 C degrees by a non-contact temperature device. Pour samples into the hopper by using a continuous or segmented pour from multiple directions around the hopper Rotate the sample cans in a clockwise direction after each split Repeat until the specified sample size is achieved. THE END QUESTIONS?? 9

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15 8/14/2017 Standard Method of Test for Bulk Specific Gravity of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens CDOT CP 44 AASHTO T Purpose This procedure provides methods for determining bulk specific gravity to calculate the percent relative compaction of HMA and air void analysis. The Bulk Sp G is also used in determining the correlation factor for nuclear density gauges. 1

16 8/14/2017 Method A Laboratory Compacted Specimens for 100mm and 150mm Diameter Specimens Testing Apparatus required Balance, with suspension apparatus. Wire of the smallest practical size at the penetration point of the water surface. Water bath with overflow outlet. Flannel or terry cloth towel 2

17 8/14/2017 Specimen Preparation After removal from mold, allow specimen to cool to room temperature. Place cooled, dry specimen on scale and record dry mass. Immerse specimen in 77 +/- 1.8 F water bath for 4 +/- 1 minute. Record immersed weight. Remove specimen from water and quickly blot to SSD condition with a wet, freshly rung out terry or flannel cloth. Quickly place specimen on scale and record the SSD weight. where: Bulk Specific Gravity Calculation G mb = A ( B - C) A = mass (in grams) of dry sample in air B = mass (in grams) of SSD sample, in air C = mass (in grams) of sample in water 3

18 8/14/2017 Percent Relative Compaction Percent Relative Compaction Bulk Specific Gravity X 100 Maximum Specific Gravity Air Voids (Va) Calculation Va Rice Bulk Rice x100 or Air Voids 100 % Relative Compaction 4

19 8/14/2017 Convert Specific Gravity (Gs) to pounds per cubic ft (pcf) CDOT uses: Specific gravity x 62.4= pcf Pcf / 62.4 = specific gravity Questions?? 5

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21 8/14/2017 Standard Method of Test for Theoretical Maximum Specific Gravity of Asphalt Paving Mixtures CDOT CP 51 AASHTO T Purpose This method covers the determination of the maximum specific gravity of uncompacted asphalt paving mixtures. This method will assist with determining: relative percent compaction percent air voids 1

22 8/14/2017 Apparatus Required Balance, with ample capacity and sensitivity. Heavy walled volumetric flask or other container. Flat, transparent cover plate. Fine wire mesh. Calibrated thermometer, ASTM 17 C. Vacuum system, 3.7 ±0.3 kpa, (28 ± 2 mm Hg). Residual pressure manometer or pressure gauge. Procedure Flask calibration. Sample preparation. Test. Calculations. 2

23 8/14/2017 Flask Calibration Perform once per month. Fill flask with water. Verify water temperature is 77 ± 1 F (25.0 ± 0.5 C). Overfill flask and level off with cover plate. Determine and record the mass of flask, water and cover plate. Identify and record the flasks and cover plate(s). Average of last three determinations and record. Sample Preparation Samples shall be obtained according to (CP 41) T168. Samples shall be split according to (CP 55) T The sample size is based on the nominal maximum aggregate size of the mixture (Table 51-1). Two separately taken identical test specimens shall be obtained and not recombined at any time. 3

24 8/14/2017 TABLE 51-1: Required Sample Mass for Various Nominal Maximum Sizes of Aggregate Nominal Maximum Size of Aggregate Number and Minimum Mass of Specimens Inches MM Specimens X grams X 3000g X 1500g ¾ X 1000g ½ X 750g 3/ X 500g No X 500g Voids Analysis If laboratory or field produced specimens are to be compacted for voids analysis using CP-L 5115, the specimens used to determine the theoretical maximum specific gravity should be short-term aged using the same procedure as the specimens being compacted. Specimens maintained at a temperature above 200 F (94 C) for 1 hr or more do not require additional aging. 4

25 8/14/2017 Sample Prep - Continued Separate the fine particles of each sample so that they are no larger than ¼ inch. Take care not to fracture mineral particles. If mixture is not sufficiently soft to be separated, mixture may be warmed only until they can be so handled. Cool samples to room temperature Test Tare flasks or record mass of each empty flask. Place samples into flasks. Record mass of each sample. Fill flask with water (approx. 25 C) to a minimum of one inch above sample. 5

26 8/14/2017 Test (continued) If the potential presence of lime in asphalt mixture needs to be determined, add 2-4 drops of phenolphthalein alcohol indicator Let rest 10 seconds, to show potential presence of lime Remove entrapped air under a partial vacuum of 3.7 ± 0.3 kpa (28 ± 2 mm Hg) for 15 ± 2 minutes. Agitate the samples and flasks at 2 minute intervals (for 15 ± 5 s) or continuously with mechanical device. Turn vacuum off, not faster than 8 kpa/sec (60 mm/s Hg). Fill flasks with water (@ 25.0 ± 0.5 C). Stir sample with rod, if necessary. Finish filing flask with 77 F water & slip lid onto flask. Place flask in 77 ± 1 F (25.0 ± 0.5 C) water bath. Bring the contents of the flasks to 25.0 ± 1.0 C (77 ± 1.8 F ), check for air bubbles, remove any found under the lid, replace lid, determine the mass of the flask, water, sample and cover plate for each sample. The mass shall be determined 10 ± 1 minutes after the vacuum is released 6

27 8/14/2017 Test (continued) In lieu of a constant temperature bath as per section 6.5, determine the calibration masses at various test temperatures. Determine the final temperature of the samples. Make the appropriate density corrections. This process should be used with all suitable containers, not just the glass flasks. Test (continued) If the aggregate is not completely coated: CDOT- Follow Method A- Dry-Back to be used if uncoated particles settle to the bottom of the flask. (They have absorbed water during the partial vacuuming process). Method B asphalt cement add in for calculating the effective specific gravity for RAP. - add in 2% to 3% virgin asphalt cement and cooling before spitting sample down for CP 51. Method C for calculating the effective specific gravity of RAS 7

28 8/14/2017 Calculations Where: G mm = A A + D - E A = mass of dry samples E = mass of samples, water, flasks and cover plate(s) D = calibration masses The specific gravities must be within of each other for a valid test. Reporting Specific Gravity As per : The specific gravity of each specimen to the nearest The average specific gravity of two specimens to the nearest

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31 8/14/2017 Standard Method of Test for Determining the Asphalt Binder Content of Hot Mix Asphalt by the Ignition Method CDOT CP L 5120 Summary of Test Method Per section 3.1, the binder in an APM sample is burned by ignition at a temperature high enough to ignite the asphalt binder fraction (due to the use of different models of ignition ovens, 8.2 of procedure is incorrect, it is not always 538 C (1000 F) 1

32 8/14/2017 Summary of Test Method (continued) Binder content is calculated by: Dividing the mass loss of the specimen after ignition by the mass of the mixture before ignition. The application of the correction factor, and the subtraction of the % of any moisture found. In Colorado, internal or external scales are used for all final weights. Summary of Test Procedure This method determines the asphalt binder content by burning the binder off by ignition, the specimen gradation is then determined with the remaining aggregate residue. Not to be used for determining binder content of cores or otherwise obtained samples from existing bituminous pavements. 2

33 8/14/2017 Overview Safety Issues Apparatus Sampling / Test Specimens Calibration Test Procedure RAP Safety Issues Wear eye protection Wear long sleeves Wear clean, heat resistant gloves Location of furnace 3

34 8/14/2017 Apparatus Forced air ignition furnace, that heats the sample by convection method or infrared heat source ignition method. Internal scale units will determine and indicate when the sample reaches a constant weight. Thermoline (NCAT) There must be an internal balance thermally isolated from the furnace chamber that is readable to 0.1g. Calibration Correction factors will be determined for the binder content and the aggregate loss. These factors will be determined for each mixture design and when mix ingredients change. This method may be affected by the type of aggregate in the mixture. A calibration factor must be performed prior to any acceptance testing. 4

35 8/14/2017 Calibration Process The calibration process should be repeated each time there is a change in the mixture ingredients. Prepare three samples proportioned according to the JMF. Step One - Perform gradation analysis on an unburned blank specimen (no binder). Calibration Process Step Two - Prepare two calibration samples at the design asphalt binder content. Burn the two samples as regular tests. Note - after mixing if the specimens are allowed to cool, heat the material at binder compaction temperature for 30 minutes in a separate pan. Ignition oven baskets are not to be preheated before beginning this test. Do not use the weight placed in the ignition oven. 5

36 8/14/2017 Aggregate Calibration (if degradation of aggregate occurred) Perform a gradation analysis on the residual aggregate. If the potential of lime needs to be determined, introduce water over the residual aggregate and add 2-4 drops of phenolphthalein alcohol indicator. Let rest 10 seconds and look for the potential presence of lime. Aggregate Calibration (if degradation of aggregate occurred) Compare the gradations of the blank (unburned) specimen and the residual aggregate to evaluate the amount of aggregate breakdown. If the difference for any single sieve exceeds the allowable difference for that sieve as listed in Table 2, then aggregate correction factors for all sieves shall be applied to all acceptance gradation test results, prior to final rounding & reporting. 6

37 8/14/2017 Aggregate Calibration Table 2 Permitted Sieving Difference Sizes larger than or equal to #8 ±5.0% Sizes larger than #200 and smaller than #8 ±3.0% Sizes #200 and smaller ± 0.5% Aggregate Calibration Example: Difference between the burned & unburned averages is greater than 3.0% on the #30 sieve, then that correction factor would be applied to all the sieves larger than #200 and smaller than the #8 on all acceptance gradation test results. Note 9: For a mix containing RAP, add the percent passing gradation values of the RAP (from mix design) to the unburned sample percent passing to get accurate percent passing. 7

38 8/14/2017 Aggregate Calibration If degradation is suspected-(section 12 CP-L 5120) Obtain a belt feed of the aggregate from the plant large enough for 4 specimens. Determine the gradation of two blank specimens. Mix 2 specimens at the design binder content, burn off the binder, perform gradation on residual aggregate. Aggregate Calibration Compare the average gradation at each sieve size for the two sets of specimens. If the gradation for any single sieve exceeds the allowable difference for that sieve according to Table 2, then apply correction factors for all sieves prior to any rounding or reporting. Calculate to the nearest 0.1%, except for the #200, it shall be to the nearest 0.01%. Report to nearest whole number, accept for the #200 sieve, to the nearest 0.1%. 8

39 8/14/2017 Calibration Process To Determine the Binder Correction Factor Determine the binder content for each sample by calculation. If the measured difference between the two burned samples is less than 0.15%, calculate the difference in binder content between the actual (optimum) and measured (mixed samples) binder contents for each sample. The calibration factor is the average of the differences between the actual and the measured asphalt contents for each sample. Binder Calibration Process If the measured difference between the two binder contents (burned samples) is greater than 0.15%: Mix up an additional two samples and repeat the procedure. Repeat procedure until the two results are within of each other 0.15% 9

40 8/14/2017 Using the Ignition Oven w/ RAP The ignition oven can be used to determine the asphalt content of mixes containing RAP. Prior to performing the mix calibration the percent binder (P b ) of the RAP must be determined by ignition with two RAP samples or the bitumen content from the mix design may be used. Using the Ignition Oven w/ RAP As with any materials, the sampling of RAP must be done carefully to result in samples that are representative of the larger mass of material. The gradation of the samples must be representative, gradation of specimen will affect the asphalt content results. 10

41 8/14/2017 Calibration Process w/ RAP Weight of binder in RAP must be determined. As per the weight of RAP required is determined. Then has the formula for determining the weight of the binder in the RAP. The next step is to determine the weight of new binder to add, to result in the desired percent of binder for specimen. Found in covers mixing up samples using two or more RAP stockpiles. Table 1: Size of Specimen Nominal Maximum Sieve Size Specimen Aggregate Size(mm) Weight RANGE 4.75 # / ½ ¾ * * * Specimens shall be divided, each part tested, results averaged 11

42 8/14/2017 Test Procedure All production samples must have a moisture correction determination. T110 or dry the HMA specimen to constant weight at 105 ± 5 C, [CP- 43 at the specified binder compaction temperature for that mixture, as per Table 43-1 for a minimum of 3 hours] Preheat ignition oven per the manufacturer s directions. Test Specimens Weigh and record weight of sample baskets on external scale. Load test specimens into baskets 1 inch from sides. 12

43 8/14/2017 Test Specimens Record total weight of basket and specimen. Determine and record the test sample weight. Enter the sample weight into the furnace computer. Test Procedure Zero the internal scale. Open the chamber door and place the baskets into the furnace. 13

44 8/14/2017 Test Procedure Close chamber door and verify that the total weight (basket and material) equals the external recorded weight within ± 5 g. Differences greater than 5 g, or a failure of the scale to stabilize, indicates the baskets are contacting the furnace wall. Initiate the test by pressing the start button. This will lock the chamber door and start the combustion blower. Allow the test to continue until the stable light and audible stable indicator indicate the test is complete (the change in weight is less than 0.01% for three consecutive minutes). Press the stop button to unlock the chamber door. 14

45 8/14/2017 Test Procedure Open the chamber door. Remove the baskets and allow the test specimen to cool sufficiently until it can safely handled. If the internal scale is being used to determine the percent binder, remove the ticket and report the percent binder. If the correction factor was not entered into the furnace, apply the correction factor before reporting the percent binder. Test Procedure If the external scale is being used to determine the percent binder; Weigh the basket assembly containing the residual aggregate and record the weight. The amount of time elapsed between the removal from the furnace and weighing on the external scale should be the same for correction factors and plant produced material (± 5 minutes). 15

46 8/14/2017 Test Procedure Determine the uncorrected asphalt binder content. Determine the corrected asphalt binder content by applying the Correction Factor and subtracting any moisture content. Calculations P ( ) = P ( ) + C F -P b c o r r b u n c o r r w Where: Pb(corr) = Asphalt binder content of field produced specimens corrected for the aggregates and asphalt binder sources Pb(uncorr) = Uncorrected asphalt binder, determined by the mass of the test specimen C F = Calibration factor, percent by weight of the HMA sample Moisture content (percent water) P w = 16

47 8/14/2017 Precision Allowable Standard Deviation Single lab 0.20% RAP Mix Multi lab 0.40% RAP Mix Questions? 17

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49 8/14/2017 Standard Method of Test for Determining Moisture (Water) or Volatile Distillates Content of Asphalt Paving Mixtures CP 43 Scope: This procedure covers two methods for the quantitative determination of moisture in Asphalt Paving Mixtures. The procedures are intended for the determination of moisture content or volatile fraction in Asphalt Paving Mixtures. The methods are intended to apply to samples of Asphalt Paving Mixtures used in verification and quality control from the points of acceptance designated in the Schedule for the Minimum Materials Sampling, Testing and Inspection. 1

50 8/14/2017 Method A Apparatus; Microwave oven - Having variable time and power controls. Pyrex dish (or other suitable dish) capable of holding the entire test specimen being tested. Balance Having sufficient capacity and sensitivity to 0.1g. Method A Procedure for calibrating the microwave Determine the Variable Power setting: Set the variable power control to approximately 50% power. Place 550 ± 50 ml of water of tap water in a Pyrex container, record the temperature of the water (T1). 2

51 8/14/2017 Method A Procedure for calibrating the microwave (continued) Set the microwave oven timer for five minutes and heat 550 ml of water. Record the temperature (T2). The difference between the temperature T1 and T2 should be 75 F ± 10 (42 C ± 6 ). If the difference is too low (or high) increase (or decrease) the variable power setting and repeat the process. Method A Microwave Procedure Place a specimen in a clean, glass, dry, tarred container and obtain the sample mass to the nearest 0.1g. The sample weight should be: 550 ± 50 g for Grading S and SX mixes 2000 g for Grading SG mixes 3

52 8/14/2017 Method A - Procedure Dry the specimen in the microwave oven using the variable power setting determined previously. Continue to dry the test specimen until the mass of the specimen does not change after further heating cycles for a 5 minute period. Care should be taken to avoid overheating the specimen ~ an indication of overheating is blue smoke. Calculations Determine the percent moisture to the nearest 0.01% as follows: A B Percent Moisture X 100 A Where A Wet weight ( mass) of test Where B Dry weight ( mass) of test specimen specimen 4

53 8/14/2017 Method B Drying Oven Thermostatically controlled forced draft oven. Specimen container Capable of holding the entire test specimen being tested. Balance Having sufficient capacity and sensitivity to 0.1g. Miscellaneous Knives, spatulas, scoops, tools, etc., as required in applicable CP s and CP-L s. Method B Procedure (Oven) Place the specimen in a clean, dry, tarred container and weigh to the nearest 0.1g. The sample weight should not be less than: 500 g for Grading S and SX mixes 2000 g for Grading SG mixes Dry the specimen in the oven at the specified binder compaction temperature for that mixture (See table 43-1), for a minimum of 3 hours. (Table 43 has been updated to include temperatures for PG 70-28) 5

54 8/14/2017 Method B Procedure (Oven) Remove the specimen and immediately weigh to the nearest 0.1g. Place the specimen back into the oven to continue drying, checking the mass of the specimen every ½ hour, ±5 minutes. The specimen is considered dry when the loss in mass is less than or equal to 0.00% Calculations Determine the percent moisture to the nearest 0.01% as follows: A B Percent Moisture X 100 A Where A Wet weight ( mass) of test Where B Dry weight ( mass) of test specimen specimen 6

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57 8/14/2017 Standard Method of Test for Asphalt Binder Content of Asphalt Mixtures by the Nuclear Method AASHTO T 287 CDOT CP 85 Asphalt Cement Content of Asphalt Mixtures by the Nuclear Method Purpose This method covers the determination of the asphalt cement (binder) mixture with a nuclear gauge. This method is a rapid determination of binder content (AC, binder). This procedure is sensitive to the type & gradation of aggregate, hydrated lime, percentage & source of binder. 1

58 8/14/2017 Purpose Measures total hydrogen in sample, including any moisture in the form of water. Moisture correction must be performed (CP 43). When using RAP in mix design, the RAP used in the calibration samples must be uniform in gradation, asphalt content and asphalt type. Required: Samples of binder and aggregate for the calibration process shall be sampled and prepared per procedure. Field samples of mix for binder content determination shall be obtained and reduced to test specimen size as per CP 55. Prior to gauge operation: stationary location away from water away from other nuclear testing devices 33 feet (10 m) 2

59 8/14/2017 Required Apparatus Content gauge. 3 or more metal sample pans #9 clean & undamaged condition. Metal plate or plywood (or wooden survey stake). Steel straightedge approx. 18 inches in length. Balance, 33 lb (15 kg), readable to 0.1 g. Large mixing bowl, misc. hand tools. Ovens. Microwave oven (CP - 43) for moisture determination. Thermometer from o F (10 to 300 o C). Procedure Steps Standardization Sample preparation Aggregate count Calibration Moisture content Test 3

60 8/14/2017 Standardization (background) Top of gauge & surrounding area by 3 feet free of any hydrogenous type materials or personnel. Gauge empty and clean. Warm-up gauge a minimum of 20 minutes. Obtain background count for 16 minutes or a minimum 8 minutes. ± 1% from previous count. Statistical stability once per month. Sample Preparation Obtain binder sample from job or supplier. Obtain aggregate samples from job or supplier. Obtain lime samples from job or supplier. Dry aggregates at 149 ± 8 C (300±15F) for a minimum of 3 hours or to constant weight. Heat binder to mixing temperature. Use job mix formula to blend aggregates in the correct proportion. 4

61 8/14/2017 Dry Aggregate Count Heat aggregates, bowls, sample pans and tools to 300 ± 15 F. Fill pan half full. Drop 1 inch four times to compact. Fill pan above rim. Repeat dropping 1 inch four times. Level off with straight edge using a sawing motion strike it off so it is level with the rim of the pan. Dry Aggregate Count (continued) Record weight. Record temperature. Obtain and record count (16 minutes), repeat approximately once per week. Run to ensure that changes in the aggregate do not occur unnoticed. If a significant change is noted in this count ± 0.5 %, a new calibration should be run. 5

62 8/14/2017 Mixing Samples Aggregates should be proportioned to the JMF. Correct amount of lime should also be mixed in with aggregates and sample hydrated before addition of binder. Mix samples with correct amount of properly graded binder. Mixing Samples How much binder do you add? One formula is: Wb= (Ws x Pb)/(100-Pb) Where: Wb = Weight of binder, Ws = Weight of Stone, Pb = Percent of Binder. Assume 7000g of stone and 5% binder required. Example: Wb= (7000X5.0)/( ) Wb= 35000/95 Wb= 368.4g 6

63 8/14/2017 Calibration Curve Generation Two Methods can be used: Method A each lab prepares & tests their own pans. Use same base weight, so can exchange pans (best practice). Use optimum pan to establish base weight (recommended). Calibration Curve Generation Method B sample pans are prepared in the contractor s lab & then passed on to the CDOT lab or their designated consultant lab. CDOT or designated consultant representative, has the option to witness calibration process. When not able to witness (or to check calibration in different testing location) prepare a sample at optimum binder content. If results vary by more than 0.20% from the optimum, a new gauge calibration is required. 7

64 8/14/2017 Calibration Curve Generation Dry 300 ± 15 F Proportion dry aggregates as per JMF and place in oven along with binder & all mixing apparatus in mixing temp. as per PG Binder specified. If RAP is being used, the percent binder in the RAP must be known and the gradation of the RAP used must uniformly match the RAP gradation used in the mix design. Calibration Curve Generation Mix a minimum of 3 calibration pans (commonly more): optimum, +1%, -1% or range (commonly at 0.5% increments) expected on the project. Fill pan half full Level sample Fill pan above rim 8

65 8/14/2017 Calibration Continued If this is the first pan, the weight that fills the pan well becomes the base weight for all the other calibration pans & test samples during production. The corners should be filled and normally the optimum pan should be the first pan made during calibration to establish the base weight. Calibration Continued The sample should then be compacted at a temperature between 250 and 300 F. Obtain and record temperature of first sample to establish the calibration temperature. All samples during calibration should then be within ± 10 F of this temperature. 9

66 8/14/2017 Calibration Continued Place sample in the gauge and obtain and record a 16 minute count. The result from the calibration pans should result in a correlation factor of to to be a valid calibration. If less than 0.999, new pans should be mixed and calibration run again. At conclusion, perform an additional background count. Variation greater than 1% from previous background count is unacceptable. 10

67 8/14/2017 Test Procedure Split out 2 samples, one for testing of %AC and one determining the %moisture from the field sample. Two methods can be used for determining the %moisture in CP 43: Method A Microwave or Method B Convection Oven. Fill pan half full. Level material in pan. Finish filling pan to base weight within 5 g. Test Procedure (cont.) Check temperature prior to compaction (should be between 250 F and 300 F). Compact sample. If using a gauge that does not compensate for temperature, the test sample temperature should be between F when placed in the nuclear gauge. (use temperature within 10 of correlation temperature) Obtain 16 minute gauge count, record count & %Binder from gauge display. 11

68 8/14/2017 Test Procedure continued Correct the %Binder from gauge display by subtracting the % moisture (if it is determined that the sample contains moisture) and document on the CDOT form 106 or any approved reporting form. 12

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71 8/14/2017 Test for Reducing Field Samples of Aggregate to Testing Size CDOT CP 32 AASHTO T 248 Purpose of Splitting These methods provide for reducing large samples of aggregate to measure characteristics in a manner that the smaller test portion is most likely to be a representation of the larger sample, and thus of the total supply. 1

72 8/14/2017 Aggregates must be sampled in accordance with CP 30. Samples must be split properly to obtain representative test specimens. Methods Method A - riffle type splitter Method B quartering Method C Selection by scoop (CDOT) Miniature stockpile method (AASHTO) 2

73 8/14/2017 Riffle Apparatus Riffle type splitter with variable size openings. Hopper to retain sample or flat scoop (feeder pan) equal in length to the overall assembly of chutes. Collection pans, minimum of two (2), equal in length to the overall assembly of chutes. Splitter brush to clean chutes of adhering fines. Quartering Apparatus 6 x 8 quartering canvas or Clean, hard, level surface (AASHTO) Flat, square end shovel 3

74 8/14/2017 Scoop & Miniature Stockpile Apparatus (Fine Aggregate Only) Large flat bottomed mixing pan (CDOT) or a clean, hard, level surface. Small, flat, square end scoop. By Riffle Splitter Riffle splitting is always preferable to hand quartering. Proper size openings required. Opening shall permit easy passage of the largest particles in the sample. For variable splitters the openings should be 1.5 times the size of the largest particles 4

75 8/14/2017 Method A - Riffle Splitter An even number of equal width chutes, but not less than 8 for coarse, or 12 for fine aggregates The splitter shall be equipped with a hopper or straight-edged pan which has a width equal or slightly less the overall width of the assembly of chutes. Sample at SSD or drier. Two procedures to split sample: o o Hopper Scoop (feeder pan) Riffle Splitter Control Flow Hopper (CDOT) Sample poured into the closed hopper from the sample container. Use all material. Uniformly distribute from edge to edge. Open release handle and allow the sample to flow freely through the chutes. The first split that is then reintroduced to the splitter assists in mixing the sample. 5

76 8/14/2017 Riffle Splitter Control Flow Hopper (CDOT) Then remove both pans from the splitter. Save material in one pan for other tests. Pour half of the remaining pan into the hopper Reverse ends of pan. Pour the remaining sample into the hopper. Riffle Splitter Control Flow Hopper (CDOT) Uniformly distribute material in hopper. Open release handle and allow the sample to flow freely through the chutes. Use alternate pans for further reduction. Splitting is continued until the sample is reduced to the required specimen size. 6

77 8/14/2017 Riffle Splitter (AASHTO) Splitting continued from one side until sample reduced to required specimen size Riffle Splitter without control hopper (CDOT) Place entire sample in a large mixing pan and mix thoroughly. Scoop the material from the pan with the feeder pan. Uniformly distribute in feeder pan. First, slowly pour half the sample from one side. 7

78 8/14/2017 Riffle Splitter without control flow hopper (CDOT) Pour the other half from the other side. Continue until entire sample has been passed through the chutes. Use alternate pans for further reduction to desired specimen size. Method B -Quartering Sample deposited on clean, hard, level surface or canvas (6 X 8 canvas). Mix material thoroughly by turning the entire sample over onto itself 3 times. 8

79 8/14/2017 Method B -Quartering Material shoveled into cone. Cone flattened at apex into in circular layer. Diameter equals approx. 4-8 times the thickness. Method B -Quartering Uniform thickness. Sample divided into two equal parts using a square shovel, pipe or stick under canvas if surface is uneven. 9

80 8/14/2017 Method B -Quartering Procedure repeated at 90 degrees. Diagonal opposite quarters removed [include all fines]. Remaining two quarters re-mixed. Procedure repeated until sample is reduced to required size. Method C Miniature Stockpile (CDOT Scoop) Only for fine grained materials (minus 3/8 inches (9.5mm). Sample should be damp. Sample deposited into large pan and mixed 3 times. Form into conical pile. Flatten pile (as in quartering). Scoop to full depth of material. 10

81 8/14/2017 Method C Miniature Stockpile (CDOT Scoop) Mix and sample to minimize the loss of particles. Portions selected from five (three) locations. Portions combined for required weight. Methods for reducing samples when using a mechanical splitter containing Free Moisture Dry to at least SSD condition, using temps that do not exceed those specified for any tests. Then split to specified size. OR Preliminary split with mechanical splitter having chute openings 1½ or more to reduce large sample to not less than 5000gr. Then dried as above and further reduced to desired size. 11

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83 Standard Method of Test for Materials Finer Than mm (No. 200) Sieve in Mineral Aggregates by Washing and the Sieve Analysis of Fine and Coarse Aggregate. CDOT uses both: CDOT CP 31 AASHTO T 11 / T 27 Summary The weight required (after drying) for this procedure, is based on the nominal maximum particle size. The -200 wash is performed to remove the finer material from the coarser particles for a more efficient result. The aggregate gradation is the distribution of particle sizes expressed as a percent of the total weight of the sample. The gradation is determined by passing the material through a series of sieves stacked with progressively smaller openings and weighing the material retained on each sieve 1

84 Apparatus Required Balance, with ample capacity and sensitivity (0.1 g) Sieves For the -200 wash, a nest of two sieves, the lower a No. 200 and the upper with openings in the range of No. 8 and No. 16 For the Sieve Analysis, additional sieves, conforming to AASHTO M92 and ASTM E11 Container, sufficient in size to contain the sample covered with water and to permit vigorous agitation without any loss of the sample or water Oven or hot plate. Test Samples Aggregates must be sampled in accordance with CP 30. Aggregates must be mixed and reduced to test specimen size in accordance with CP 32 2

85 CP 31 Sieve Analysis & Materials Finer than the No, 200 by washing AASHTO T 11 & T 27 (found in AASHTO portion of handout) shall be used to determine the sieve analysis of fine & coarse aggregates with the following exceptions: Table 31-1 still used for minimum sample mass. Moisture Correction process can still be used, according to following procedure. CP 31 Split material into two approximately equal samples. Dry one sample to constant mass in oven at 230 F ± 9 oven or use a hotplate to determine % moisture. Determine dry weight of second sample: Wet weight/100 + %moisture X 100 = Corrected Dry Weight 3

86 Aggregate Nominal Maximum Size square openings, Test Samples-Coarse Aggregate Table 31-1 Minimum Mass of Test Sample (AASHTO) (kg) Minimum Mass of Test Sample Lb (kg) 3/ (1.0) ½ (1.5) ¾ (2.0) (2.5) (5.0) (7.5) Procedure Dry the sample to constant 110 ± 5 C (230 ± 9 F) and determine the mass of the test sample. A hot plate is acceptable for drying if the aggregate temperature can be maintained above the boiling point of water. Use moisture correction method. 4

87 Procedure for the -200 wash Place the sample into container and cover with water. Add wetting agent if desired. Agitate the test sample with sufficient vigor to separate the particles finer than the No. 200 sieve and to bring the material into suspension. Procedure, -200 wash (cont.) Immediately pour the wash water over the nested sieves avoiding the decantation of coarser particles of the sample. 5

88 Procedure, -200 wash (continued) The entire sample may be placed into the upper sieve and washed until the coarser fraction is clean, however all water must pass through the No. 200 sieve. Add a second charge of water (no wetting agent). Agitate and decant. Repeat this operation until the wash water is clear. Procedure, -200 wash (continued) Return all material retained on the sieves to the container. Dry the washed aggregate to a constant mass at 230 ± 9 F (110 ± 5 C) A hot plate is acceptable if the aggregate temperature can be maintained above the boiling point of water Cool to room temperature, determine and record the dry mass of the material. 6

89 Before/After Sieve Weight Check Weigh & record weight of washed sample after drying prior to placing in the stack. Weigh & record weight of material from each sieve either individually or accumulatively. Final total weight should not differ by more than 0.3% of the original dry mass of the washed and dried sample. Difference OriginalDryMass %. Sieving Procedure Separate the specimen over a series of suitable. Size sieves, including those required by the specifications, manually or mechanically. Do not overload sieves: 12 inch = Approx. 500g 8 inch = Approx. 200g 7

90 Sieving Adequacy Annual calibration of shaker. Test using different material types. Hand shake each individual sieve for additional 1 minute. Pan on bottom and lid on top. Hold at slightly inclined angle and tap sharply with heel of hand. 25 taps at each of 6 locations around the sieve = 150 taps. Not more than 0.5% by weight of the total sample can pass. Loss / original dry mass x 100= 0.5% Procedure, Sieve (cont) Determine and record the mass of material retained on each sieve to 0.1g individually cumulatively 8

91 Procedure Calculate the Moisture content M/C = Wet Dry/Dry Calculate the original dry mass from the percent moisture when using moisture correction methods. Wet Weight (100 + %M) X 100 = Original Dry Weight Calculate percent retained to 0.1% Sieve Weight Original Dry Weight X 100 = % Retained Calculate the percent passing and report to nearest whole number except No. 200 to 0.1% 100 -% retained = % Passing Cumulative Weights Individual Weights 9

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95 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM Standard Method of Test for Asphalt Binder Content of Asphalt Mixtures by the Nuclear Method AASHTO Designation: T SCOPE This procedure covers the quantitative determination of the asphalt binder content of asphalt mixtures by testing a sample with a nuclear gauge that utilizes neutron-thermalization techniques. The values expressed in SI units are to be regarded as the standard. The inch-pound equivalents of the SI units may be approximate. Nuclear gauge operations and maintenance are not covered in detail. See the manufacturer's manual for details. This test method involves potentially hazardous materials, operations, and equipment. This method does not purport to address all of the safety concerns associated with its use. All operators will be trained in radiation safety prior to operating nuclear gauges. Some agencies require the use of personal monitoring devices such as a thermoluminescent dosimeter or film badge REFERENCED DOCUMENTS AASHTO Standards: M 231, Weighing Devices Used in the Testing of Materials R 66, Sampling Asphalt Materials R 76, Reducing Samples of Aggregate to Testing Size T 2, Sampling of Aggregates T 11, Materials Finer Than 75-μm (No. 200) Sieve in Mineral Aggregates by Washing T 27, Sieve Analysis of Fine and Coarse Aggregates T 110, Moisture or Volatile Distillates in Hot Mix Asphalt (HMA) T 168, Sampling Bituminous Paving Mixtures T 255, Total Evaporable Moisture Content of Aggregate by Drying T 329, Moisture Content of Asphalt Mixtures by Oven Method SUMMARY OF METHOD This procedure can be used for rapid determination of the asphalt binder content of asphalt mixtures. It is suitable for quality control and acceptance testing for construction and for research and development applications. This procedure is useful in the determination of asphalt binder content only and does not provide for gradation analysis. This procedure determines the asphalt binder content of a test sample by comparing the measured asphalt binder content with previously established calibration data. The asphalt binder content is expressed as a percentage of the mass of the asphalt mixture. Accurate results are dependent on proper calibration of the nuclear gauge to the material being tested as covered in Annex A. This procedure is sensitive to the type and gradation of the aggregate, liquid

96 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM anti-stripping additive or hydrated lime, and the percentage and source of the asphalt binder. This procedure measures the total amount of hydrogen in a sample including the hydrogen present in the form of water. Unless the test sample is totally free of water, the moisture content must be determined according to T 110 or T 329 and the percentage subtracted from the asphalt binder content measured by the nuclear gauge. Alternatively, prior to testing, the sample may be dried to a constant mass in accordance with T 329, thereby nullifying the need for a moisture correction. This procedure can be used with recycled asphalt pavement (RAP) incorporated into the asphalt mixture, provided that the RAP is of uniform gradation, asphalt binder content, and asphalt binder type. When RAP is used, the RAP should be mixed in the calibration samples in the same proportion that it will be used on the construction project APPARATUS Nuclear asphalt binder content gauge system consisting of: Neutron Source an encapsulated and sealed radioactive source; Thermal neutron detectors; Readout instrument displaying, at a minimum, the percent of asphalt binder to the nearest 0.1 percent; and Three or more stainless-steel sample pans conforming to the gauge requirements. Mechanical mixer with a 10-kg (22-lb) capacity, capable of producing a completely mixed, well- coated, homogeneous asphalt mixture. Sample containers such as paint cans or unwaxed, nonabsorbent cardboard boxes that can be closed to prevent contamination of the sample and are capable of withstanding the heating of the asphalt mixture to the mixing temperature. Sample-quartering apparatus conforming to the requirements of R 76, Method B. General-purpose balance or scale conforming to M 231, 20-kg (44-lb) capacity, readable to 0.1 g. Drying Oven capable of handling the required number of samples and sample sizes, of either of the following types: Forced-air convection oven capable of maintaining a temperature of 177 ± 3 C (350 ± 5 F). Microwave oven, determined not to be detrimental to the aggregate, capable of maintaining a temperature of 177 ± 3 C (350 ± 5 F). Leveling Plate flat, rigid plate of metal [minimum thickness of 10 mm (0.4 in.)], Plexiglas [minimum thickness of 12.5 mm (0.5 in.)], or nonabsorptive plywood [minimum thickness of 19 mm (0.75 in.)], slightly larger than the sample pans. Thermometer with a temperature range of 10 to 260 C (50 to 500 F). Assorted pans, spoons, spatulas, and mixing bowls. Radioactive materials information/calibration packet containing: Daily standard count log; Factory/laboratory calibration data sheet;

97 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM Leak test certificate; Shipper's declaration for dangerous goods; Procedure memo for storing, transporting, and handling nuclear testing equipment; and Other radioactive materials documentation conforming to local regulatory requirements PRECAUTIONS The nuclear asphalt binder content gauge may be sensitive to outside influences and therefore: Any other source of neutron radiation shall be kept at least 10 m (33 ft) from the apparatus during use; The space within 1 m (3.3 ft) of the apparatus shall be kept free of hydrogenous material such as water, plastics, asphalt binder, or asphalt mixtures during use; All personnel shall be kept at least 1 m (3.3 ft) away from the gauge during testing; and The gauge shall not be located within 10 m (33 ft) of any water supply tanks, fuel tanks, or other liquid containers subject to fluctuating liquid levels. Moving the apparatus to a different location, even within the same laboratory, may cause a change in the background radiation measurements. New background measurements, and possibly recalibration, will be necessary prior to use whenever background conditions have changed. See Sections 6 and 7 for instructions concerning calibration and background measurements CALIBRATION Perform calibrations and cross-calibrations on asphalt mixtures tested in gauges, and transfer calibrations between gauges according to Annex A STANDARDIZATION Obtain and record a background count in accordance with the manufacturer's procedure each day prior to taking test measurements or whenever the gauge has been moved or the conditions within 1 m (3.3 ft) of the gauge have changed. The measurement time for the background count should be the same as that used for the test measurements. If the background count has not changed by more than 1 percent from the previous background count, then the apparatus shall be considered stable and acceptable for use. If the gauge has been moved or if the surrounding conditions have changed, additional background counts must be obtained until the 1 percent standard is satisfied PROCEDURE Obtain a representative sample of asphalt mixture in accordance with T 168. If required, reduce the sample to the approximate test size by splitting or quartering according to R 76, Method B. It is recommended that testing be performed while the asphalt mixture is still hot, and not reheated, if possible. If the asphalt mixture cools and reheating is necessary, heat it to the midpoint of the

98 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM compaction temperature range for the asphalt binder used in the asphalt mixture. Determine the mass of a clean gauge-sample pan, and tare the pan on the scale. Place the asphalt mixture into the pan until it is about half full. Lightly tamp the asphalt mixture in the pan with a preheated spoon or spatula. Place additional asphalt mixture into the pan until the required mass, as determined in Annex A, is reached within ±5 g. Place the leveling plate on top of the asphalt mixture immediately after filling the pan. Compact the sample into the pan until it is level with the top of the pan by pressing down on the plate. Sight across the top of the pan to ensure that the asphalt mixture does not protrude above the pan. Record the mass of the asphalt mixture compacted into the pan. The mass shall be within ±5 g of the target mass. Note 1 If the gauge does not have temperature-compensation capability, measure and record the temperature of the compacted specimen. This temperature must be within ±5 C (9 F) of the calibration-test-specimen temperature. If the gauge has the ability to store multiple calibrations, activate the calibration for the particular asphalt mixture. Place the pan into the gauge, and perform a 4-min count. Determine the uncorrected asphalt binder content by direct readout from the gauge, calibration graph, or formula supplied by the manufacturer. Record the uncorrected asphalt binder content from the 4-min reading to the nearest 0.1 percent. Using a representative portion of the original sample or a portion of the material removed from the gauge pan, determine the moisture in the asphalt mixture according to T 110 or T 329, and record it to the nearest 0.1 percent. Alternatively, prior to testing, the sample may be dried to a constant mass in accordance with T 329, thereby nullifying the need for a moisture correction CALCULATION When determined, subtract the moisture content from the uncorrected asphalt binder content. Record this value as the corrected asphalt binder content REPORT Report the following information: Make, model, and serial number of the nuclear asphalt binder content gauge; Date and source of the calibration; Date of the test; Name and signature of the operator; Background count for the day of the test; Asphalt mixture identification; Aggregate type and sources;

99 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM Asphalt binder grade and source; When used, source and amount of liquid anti-stripping additive or hydrated lime; Calibration sample mass and temperature; Test-sample mass and temperature if the gauge does not have temperature-compensation capability; Gauge reading; and Corrected asphalt binder content value to the nearest 0.1 percent KEYWORDS Asphalt binder content; asphalt mixture; background count; calibration; cross-calibration; nuclear density gauge. ANNEXES (Mandatory Information) A1. A1.1. SCOPE This annex covers the preparation of samples for, and the calibration of, nuclear asphalt binder content gauges. Job-mix formula (JMF) calibration and cross-calibration of master and field gauges are included. A2. A2.1. A2.2. SAMPLING Obtain samples of aggregate according to T 2. Approximately 50 kg (110 lb) will be required for the calibration specimens. Obtain samples of asphalt binder according to R 66. Approximately 4 L (1 gal) will be required. Note A1 The more accurately the ingredient materials (including liquid anti-stripping additive or hydrated lime) are prepared to match the JMF, the closer the calibration points will be to the production asphalt mixture; and, therefore, the more accurate the results will be. A3. A3.1. A3.2. A3.3. A3.4. AGGREGATE PREPARATION When used, hydrate the appropriate amount of lime on the aggregate. Dry the aggregate to a constant mass in accordance with T 255. Separate the aggregate blend by dry-sieving on the specified sieves, including the minus 75-μm (No. 200) material. Calculate the required cumulative mass for each specified sieve using the following formula:

100 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM (A3.1) where: X = the required, cumulative batch mass for each specified sieve (g); T = the initial, total aggregate mass (g); and P = the percent passing for each specified sieve according to the JMF. Perform an aggregate dust correction as follows: Prepare a washed-gradation sample from the masses calculated in Section A3.4. Perform a washed gradation according to T 27 and T 11. Calculate the corrected batch mass for each specified sieve for the calibration points using the following formula: (A3.2) where: Z n = the adjusted, cumulative batch mass for any sieve size, n (g); X = the prewash, cumulative batch mass for each specified sieve (g); and Y = the post-wash, cumulative batch mass for each specified sieve (g). Blend the aggregate together at the proper proportion to match the JMF using the masses calculated in Section A A4. A4.1. A4.2. A ASPHALT BINDER PREPARATION Heat a minimum of 2 L (0.5 gal) of asphalt binder to the midpoint of the mixing temperature range in a covered container(s). When used, add the appropriate amount of liquid anti-stripping additive to the asphalt binder. Use the asphalt binder as soon as it reaches the midpoint of the mixing temperature range. If this operation is not possible, maintain the asphalt binder at this temperature for no more than 4 h. Do not cool and reheat the asphalt binder. Method A Asphalt binder percent by mass of the asphalt mixture. Calculate the mass of asphalt binder for each calibration point as follows:

101 Standard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM (A4.1) where: B = the mass of the asphalt binder to the nearest 0.1 g; E = the mass of the asphalt mixture (g); and P bm = the percent of asphalt binder by total mass of the asphalt mixture, expressed as a decimal. Asphalt binder contents will be chosen at the optimum asphalt binder content and at increments of ±0.8 percent from the optimum asphalt binder content. The minimum four samples are at 0.8 percent below optimum, at optimum, at 0.8 percent above optimum, and at 1.6 percent above optimum. Calculate the mass of aggregate required for each calibration point as follows: (A4.2) where: A = the mass of the aggregate to the nearest 0.1 g. Method B Asphalt binder percent by mass of the aggregate. Calculate the mass of aggregate for each calibration point as follows: (A4.3) where: P ba = the percent of asphalt binder by mass of the aggregate, expressed as a decimal. Asphalt binder contents will be chosen at the optimum asphalt binder content and at increments of ±0.8 percent from the optimum asphalt binder content. The minimum four samples are at 0.8 percent below optimum, at optimum, at 0.8 percent above optimum, and at 1.6 percent above optimum. Calculate the mass of asphalt binder required for each calibration point as follows: (A4.4) A5.1. PREPARATION FOR SPECIMENS

102 Standard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM The aggregate and asphalt binder materials must be heated to the midpoint of the mixing temperature range for that asphalt binder. Once these materials have stabilized at that temperature, proceed with the following steps: Determine the mass of the heated mixing bowl to the nearest 0.1 g. Place a heated aggregate specimen, of the required mass to the nearest 0.1 g, in the mixing bowl. Form a crater in the aggregate large enough to hold the required mass of asphalt binder. Place the mixing bowl on the scale. Add the required, preheated asphalt binder mass, to the nearest 0.1 g, into the aggregate crater. Mechanically mix the aggregate and asphalt binder rapidly for a minimum of 2 min until they are thoroughly blended. Check the bottom and sides of the bowl for unmixed aggregate and asphalt binder. If necessary, remix the sample by hand until it is thoroughly mixed. Note A2 Hand-mixing is not recommended. However, mixing may be performed by hand in a large bowl. In this case, the mixing time shall be a minimum of 5 min, but it may be longer to ensure thorough mixing. Remove the asphalt mixture from the bowl, and determine the mass of the empty bowl to ensure that all material has been removed. The mass of the bowl shall be within ±5 g of the mass determined in Section A5.2. If it is not, scrape the bowl with a spatula, and deposit the excess into the sample, until the mass of the bowl is within the tolerance. A6. A6.1. TARGET MASS DETERMINATION An initial, or butter batch is prepared to determine the mass to be used for the calibration samples using an asphalt binder/aggregate blend approximating the real batches. Based on experience with aggregate specific gravity and gradation, the target mass will be from 6000 to 9000 g. Note A3 To find an approximate starting mass, place the dry aggregate in a gauge-sample pan. Fill the pan half full; then drop it from a height of 25 mm (1 in.). Fill the pan just over full, and strike it off even with the top. Determine this mass, and add 10 percent to obtain an approximate starting mass. A6.2. A6.3. A6.4. A6.5. A6.6. A6.7. Mix the preheated aggregate and asphalt binder according to Section A5. Determine the mass of a clean gauge-sample pan, and tare the pan on the scale. Place the asphalt mixture into the pan until it is about half full. Lightly tamp the asphalt mixture in the pan with a preheated spoon or spatula. Place the remaining asphalt mixture into the pan so that the asphalt mixture is mounded about 13 mm (0.5 in.) above the top of the pan. Place the leveling plate on top of the asphalt mixture immediately after filling the pan. Compact the sample into the pan until it is level with the top of the pan by pressing down on the plate. Sight across the top of the pan to ensure that the asphalt mixture does not protrude above the pan. Determine and record the mass of the asphalt mixture compacted into the pan. This value is the target mass. The subsequent calibration and sample specimens must be within ±5 g of this mass. A7.1. CALIBRATION (GENERAL)

103 tandard Method of Test for Asphalt Binder Content of Asphalt Mixture... of /8/17, 11:11 AM The type of aggregate, source and grade of asphalt binder, liquid anti-stripping additive or hydrated lime, and asphalt mixture gradation will influence the test results obtained using this procedure. Accordingly, a calibration curve must be developed for each combination of these factors. The calibration curve must cover the range of expected values found in field samples. The limits for the calibration curve must consider the allowable range of asphalt binder content plus the allowable aggregate moisture (which reads as asphalt binder in the gauge). At a minimum, use 0.8 below, optimum, 0.8 above, and 1.6 percent above the optimum asphalt binder content when making the calibration-curve pans. A8. A8.1. A8.2. A8.3. A8.4. A8.5. A8.6. A8.7. A8.8. A8.9. JMF CALIBRATION Prepare four aggregate samples using the target mass determined in Section A6.7. Place them in separate pans designed for, and capable of, transferring the dry aggregate into a mixing bowl with a minimum loss of aggregate. Place them in an oven set at the midpoint of the mixing temperature range for the asphalt binder to be used. Determine the mass of the aggregate and asphalt binder for each calibration sample according to Sections A3 and A4, respectively. Mix the preheated aggregate and asphalt binder according to Section A5. Determine the mass of a clean gauge-sample pan, and tare the pan on the scale. Place the asphalt mixture into the pan until it is about half full. Lightly tamp the asphalt mixture in the pan with a preheated spoon or spatula. Place the remaining asphalt mixture into the pan so that the asphalt mixture is mounded about 13 mm (0.5 in.) above the top of the pan. Place the leveling plate on top of the asphalt mixture immediately after filling the pan. Compact the sample into the pan until it is level with the top of the pan by pressing down on the plate. Sight across the top of the pan to ensure that the asphalt mixture does not protrude above the pan. Determine and record the mass of the asphalt mixture compacted into the pan. The mass shall be within ±5 g of the target mass determined in Section A6.7. Place the pan into the gauge, and proceed in accordance with the manufacturer's instructions for the operation of the equipment and the sequence of operations. Note A4 Do not forget to perform a background count according to the manufacturer's instructions. A8.10. Repeat Sections A8.2 through A8.9 for the other calibration samples. A9. A9.1. A A PRESENTATION OF CALIBRATION DATA For gauges that generate the calibration internally to the gauge: Print or otherwise record the formula coefficients, the coefficient of fit, and the calculated percent difference for each calibration point. If the coefficient of fit is less than for a dense-graded asphalt mixture or for an open-graded asphalt mixture, or any calibration point has a calculated percent difference greater than 0.09 percent, the calibration is not acceptable and must be performed again. Store the acceptable calibration in the gauge's memory, using the JMF and an easily recognizable

104 Standard Method of Test for Asphalt Binder Content of Asphalt Mixture of 10 8/8/17, 11:11 AM calibration number, according to the manufacturer's instructions. For gauges that do not generate the calibration internally to the gauge: Prepare a calibration curve by plotting the gauge readings for the calibration samples versus asphalt binder content on linear graph paper, choosing convenient scale factors for the gauge readings and asphalt binder content. A10. A10.1. CROSS-CALIBRATION (WHEN APPLICABLE) The formula coefficients are entered into the field gauge in the transfer mode during the crosscalibration process. The new formula coefficients, when printed, will not resemble the values entered because they will change based on this relationship. For more detailed information on the formula coefficients, refer to the manufacturer's instructions. If required, a straight calibration may be performed and used instead of the transfer program. This option requires that the sample pans used for the calibration be tested in another gauge if the testing must be verified by the agency. Note A5 Some agencies cross-calibrate gauges. This process creates a relationship between the field gauge and the gauge used in the JMF calibration, allowing the testing of production asphalt mixture without the need to perform calibrations in the field. When several gauges are cross-calibrated, the asphalt mixture calibrations may be transferred to each gauge. A10.2. Prepare six calibration samples using a locally available, agency-approved aggregate, with asphalt binder contents between 3 and 8 percent at 1-percent increments. Mix the samples so that each pan of asphalt mixture equals the target mass ±5 g as determined for the aggregate. Test each sample in the master gauge using 16-min counts in the normal calibration mode. After all samples are tested, the gauge will automatically calculate a coefficient of fit. The coefficient of fit must be at least Seal each pan to prevent a change in hydrogen content, and repeat the procedure. Sealed pans must meet the same criteria as above. Note A6 To seal the pan, cut a piece of tin the size of the top of the sample pan. Seal the edges of the pan and tin lid with an epoxy. This process will seal any moisture out. A10.3. Test each of the six sealed calibration samples in the field gauge while it is in the cross-calibration mode. For each calibration sample, input the data obtained from the master gauge into the field gauge. The master and field gauges are now cross-calibrated. Note A7 Annually, or whenever a field gauge differs from the master gauge, a new cross-calibration must be performed using the sealed pans originally produced for the gauge standardization. These six pans must be checked monthly in the master gauge to verify that the counts have not changed substantially. 1 Minor editorial revisions have been made at the discretion of the authors responsible for standards on Asphalt Aggregate Mixtures (technical section 2c).

105 tandard Method of Test for Bulk Specific Gravity (Gmb) of Compacte... Standard Method of Test for Bulk Specific Gravity ( ) of Compacted Hot Mix Asphalt (HMA) Using Saturated Surface-Dry Specimens AASHTO Designation: T Release: Group 3 (August 2016) SCOPE This method of test covers the determination of bulk specific gravity (G mb ) of specimens of compacted hot mix asphalt (HMA). This method should not be used with samples that contain open or interconnecting voids or absorb more than 2.0 percent of water by volume, as determined in Sections 7.2 or 10.2 herein. If the sample contains open or interconnecting voids or absorbs more than 2.0 percent of water by volume, then T 275 or T 331 should be used. The bulk specific gravity (G mb ) of the compacted HMA may be used in calculating the unit mass of the mixture. Note 1 The values for bulk specific gravity (G mb ) obtained from T 275 or T 331 may differ. Care should be exercised when comparing test results from T 275 and T The values stated in SI units are to be regarded as the standard. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use REFERENCED DOCUMENTS AASHTO Standards: M 231, Weighing Devices Used in the Testing of Materials T 275, Bulk Specific Gravity (G mb ) of Compacted Hot Mix Asphalt (HMA) Using Paraffin-Coated Specimens T 331, Bulk Specific Gravity (G mb ) and Density of Compacted Hot Mix Asphalt (HMA) Using Automatic Vacuum Sealing Method 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials D7227/D7227M, Standard Practice for Rapid Drying of Compacted Asphalt Specimens Using Vacuum Drying Apparatus E1, Standard Specification for ASTM Liquid-in-Glass Thermometers of 6 8/8/17, 11:06 AM

106 tandard Method of Test for Bulk Specific Gravity (Gmb) of Compacte... of 6 8/8/17, 11:06 AM TERMINOLOGY Definitions: bulk specific gravity (of solids) (G mb ), as determined by this test method the ratio of a given mass of material at 25 C (77 F) to the mass of an equal volume of water at the same temperature constant mass shall be defined as the mass at which further drying does not alter the mass by more than 0.05 percent when weighed at 2-h intervals when using oven drying, or by more than 0.05 percent when weighed after at least two drying cycles of the vacuum-drying apparatus required in ASTM D7227/D7227M TEST SPECIMENS Test specimens may be either laboratory-compacted HMA or sampled from HMA pavements. Size of Specimens It is recommended that: (1) the diameter of cylindrically compacted or cored specimens, or the length of the sides of sawed specimens, be at least equal to four times the maximum size of the aggregate; and (2) the thickness of specimens be at least one and one-half times the maximum size of the aggregate. Specimens shall be taken from pavements with a core drill, diamond or carborundum saw, or by other suitable means. Care shall be taken to avoid distortion, bending, or cracking of specimens during and after the removal from the pavement or mold. Specimens shall be stored in a safe, cool place. Specimens shall be free from foreign materials such as seal coat, tack coat, foundation material, soil, paper, or foil. If desired, specimens may be separated from other pavement layers by sawing or other suitable means. Care should be exercised to ensure sawing does not damage the specimens. METHOD A APPARATUS Weighing Device The weighing device shall have sufficient capacity, be readable to 0.1 percent of the sample mass or better, and conform to the requirements of M 231. The weighing device shall be equipped with a suitable suspension apparatus and holder to permit weighing the specimen while suspended from the center of the scale pan of the weighing device. Suspension Apparatus The wire suspending the container shall be the smallest practical size to minimize any possible effects of a variable immersed length. The suspension apparatus shall be constructed to enable the container to be immersed to a depth sufficient to cover it and the test sample during weighing. Care should be exercised to ensure no trapped air bubbles exist under the specimen. Water Bath For immersing the specimen in water while suspended under the weighing device, equipped with an overflow outlet for maintaining a constant water level.

107 Standard Method of Test for Bulk Specific Gravity (Gmb) of Compacte... of 6 8/8/17, 11:06 AM PROCEDURE Dry the specimen to a constant mass at a temperature of 52 ± 3 C (125 ± 5 F). Samples saturated with water shall initially be dried overnight and then weighed at 2-h drying intervals. Recently compacted laboratory samples, which have not been exposed to moisture, do not require drying. As an alternative to oven drying to constant mass, drying the sample according to ASTM D7227/D7227M may be used. When using ASTM D7227/D7227M to achieve constant mass, perform the drying procedure at least twice, with a mass determination after each drying cycle. Cool the specimen to room temperature at 25 ± 5 C (77 ± 9 F), and record the dry mass as A (Note 2). Immerse each specimen in the water bath at 25 ± 1 C (77 ± 1.8 F) for 4 ± 1 min, and record the immersed mass as C. Remove the specimen from the water bath; damp-dry the specimen by blotting it with a damp towel, and determine the surface-dry mass as B as quickly as possible (the entire operation is not to exceed 15 s). Any water that seeps from the specimen during the weighing operation is considered part of the saturated specimen. Each specimen shall be immersed and weighed individually. Note 2 If desired, the sequence of testing operations may be changed to expedite the test results. For example, first the immersed mass C can be taken, then the surface-dry mass B, and finally the dry mass A. Note 3 Terry cloth has been found to work well for an absorbent cloth. Damp is considered to be when no water can be wrung from the towel CALCULATION Calculate the bulk specific gravity (G mb ) of the specimen as follows: (1) where: A = mass of the specimen in air, g; B = mass of the surface-dry specimen in air, g; and C = mass of the specimen in water, g Calculate the percent of water absorbed by the specimen (on a volume basis) as follows: (2) 7.3. If the percent of water absorbed by the specimen as calculated in Section 7.2 exceeds 2.0 percent, use either T 275 or T 331 to determine the bulk specific gravity (G mb ).

108 tandard Method of Test for Bulk Specific Gravity (Gmb) of Compacte... of 6 8/8/17, 11:06 AM METHOD B APPARATUS Weighing Device The weighing device shall have sufficient capacity, be readable to 0.1 percent of the sample mass or better, and conform to the requirements of M 231. Water Bath For immersing the specimen in water. Thermometer ASTM 17C (17F) as provided in ASTM E1, having a range of 19 to 27 C (66 to 80 F), graduated in 0.1 C (0.2 F) subdivisions. Volumeter 1 Calibrated to 1200 ml, or an appropriate capacity depending on the size of the test sample. The volumeter shall have a tapered lid with a capillary bore PROCEDURE Dry the specimen to a constant mass at a temperature of 52 ± 3 C (125 ± 5 F). Samples saturated with water shall initially be dried overnight and then weighed at 2-h drying intervals. Recently compacted laboratory samples, which have not been exposed to moisture, do not require drying. As an alternative to oven drying to constant mass, drying using ASTM D7227/D7227M may be used. When using ASTM D7227/D7227M to determine the constant mass, follow the drying procedure at least twice, with a mass determination after each drying procedure. Cool the specimen to room temperature at 25 ± 5 C (77 ± 9 F), and record the dry mass as A (Note 2). Immerse the specimen in the water bath at 25 ± 1 C (77 ± 1.8 F), and let it saturate for at least 10 min. At the end of the 10-min period, fill a calibrated volumeter with distilled water at 25 ± 1 C (77 ± 1.8 F), and weigh the volumeter. Designate this mass as D. Remove the saturated specimen from the water bath and damp-dry the specimen by blotting with a damp towel (Note 3) as quickly as possible (not to exceed 5 s). Weigh the specimen, and record the surface-dry mass as B. Any water that seeps from the specimen during the weighing operation is considered part of the saturated specimen. Place the specimen into the volumeter, and let it stand for at least 60 s. Bring the temperature of the water to 25 ± 1 C (77 ± 1.8 F), and cover the volumeter, making certain that some water escapes through the capillary bore of the tapered lid. Wipe the outside of the volumeter dry with a dry, absorbent cloth, and weigh the volumeter and its contents (Note 4). Record this weight as E. Note 4 If desired, the sequence of testing operations can be changed to expedite the test results. For example, first the mass of the saturated, damp-dry specimen B can be taken. Then the volumeter containing the saturated specimen and water E can be weighed. The dry mass of the specimen A can be determined last. Note 5 Method B is not acceptable for specimens that have more than 6 percent air voids CALCULATIONS Calculate the bulk specific gravity (G mb ) of the specimen as follows:

109 tandard Method of Test for Bulk Specific Gravity (Gmb) of Compacte... of 6 8/8/17, 11:06 AM (3) where: A = mass of the dry specimen, g; B = mass of the surface-dry specimen, g; D = mass of the volumeter filled with water at 25 ± 1 C (77 ± 1.8 F), g; and E = mass of the volumeter filled with the specimen and water at 25 ± 1 C (77 ± 1.8 F), g. Calculate the percent of water absorbed by the specimen (on a volume basis) as follows: (4) If the percent of water absorbed by the specimen as calculated in Section 10.2 exceeds 2.0 percent, use either T 275 or T 331 to determine the bulk specific gravity (G mb ). METHOD C (RAPID TEST) PROCEDURE This procedure can be used for testing specimens that are not required to be saved and that contain a substantial amount of moisture. Specimens obtained by coring or sawing can be tested the same day by this method. The testing procedure shall be the same as given in Section 6 or 9 except for the sequence of operations. The dry mass A of the specimen is determined last as follows: Place the specimen in a large, flat-bottom drying pan of known mass. Place the pan and specimen in an oven at 110 ± 5 C (230 ± 9 F). Leave the specimen in the oven until it can be easily separated to the point where the particles of the fine aggregate-asphalt portion are not larger than 6.3 mm ( 1 / 4 in.). Place the separated specimen in an oven at 110 ± 5 C (230 ± 9 F), and dry to a constant mass Cool the pan and specimen to room temperature at 25 ± 5 C (77 ± 9 F). Determine the mass of the pan and specimen, subtract the mass of the pan, and record as the dry mass, A CALCULATIONS Calculate the bulk specific gravity (G mb ) as given in Section 7.1 or 10.1.

110 tandard Method of Test for Bulk Specific Gravity (Gmb) of Compacte... of 6 8/8/17, 11:06 AM REPORT The report shall include the following: The method used (A, B, or C). Bulk specific gravity (G mb ) reported to the nearest thousandth. Absorption reported to the nearest hundredth. 14. PRECISION Table 1 Precision Estimates for T KEYWORDS Asphalt mixture; bulk specific gravity; hot mix asphalt; saturated surface-dry; volumeter. 1 Suitable aluminum volumeters of different sizes are available from Pine Instrument Co., 101 Industrial Drive, Grove City, PA 16127; and Rainhart Co., 604 Williams St., Austin, TX